Method for designing detachable objects using magnetic holding force

ABSTRACT

Provided is a method for designing a detachable object to an item by setting design objectives including a magnetic holding force objective needed to hold the detachable object to the item. A set of magnetic pieces are selected based on the holding magnetic force objective. An outer magnetic piece is fabricated onto the detachable object and an inner magnetic piece is fabricated and positioned within the item. The selection of the magnetic set and/or the position of the outer and inner magnetic pieces are modified until the design objectives are met.

BACKGROUND

1. Field

The present application generally relates to the design of detachableobjects, more particularly, to a method of designing detachable objectsusing magnetic holding force that meet one or more design objectives.

2. Related Art

Detachable objects are used extensively in jewelry and ornaments.Pendant connectors, permanent magnet rings, and magnetic necklace claspsare known in the prior art. Most of the magnetic necklace claspspecifies the use of a magnet that remain magnetized in the face ofstray magnetic fields, mechanical movement or shock, and a range oftemperatures. These magnets are known as permanent magnets. There arethree types of permanent magnets currently in use; alnicos, hardferrites, and rare-earth magnets. Two types of commercially availablerare-earth magnets, neodymium-iron-boron (Nd—Fe—B) and samarium cobalt(SmCo), are much stronger permanent magnets than alnicos or hardferrites. A hard ferrite magnet would have to be ten times the size ofeither of these rare-earth magnets to achieve the same pull force.

A magnet's holding strength derives from the magnet's atomic structureand from the magnet's method of manufacture. A samarium cobalt magnetholds its standard property in higher maximum temperatures than aneodymium-iron-boron magnet, but the neodymium magnet achieves a highermaximum energy product as measured in megagauss-oersteds. Samariumcobalt is more brittle than neodymium-iron-boron and more expensivebecause samarium is the least abundant of the light rare-earth elements.Sintered neodymium-iron-boron magnets processed by a melting method areabout three times stronger than bonded neodymium-iron-boron magnetsprocessed by a gluing method. Because magnetic pull force, cost, andstability are the most relevant factors to magnets used in jewelryproduction, sintered neodymium-iron-boron magnets are practical magnetsto use in manufacturing a convertible magnetic pendant clasp necklace.The use of relatively strong magnetic materials permits less magneticmaterial to be used to achieve the same magnetic strength than if weakermagnetic material were used.

One limitation of known magnetic detachable objects is their inabilityto serve as a mount for ornaments. For example, a magnetic clasp musthave a flat center if it is to serve as such a mount. If the clasp has acenter that is not flat or if the center is uneven in any way due to thepresence of integrated latches or release devices, pendant items willtilt or fall off when bumped. Another problem typically encountered withdetachable objects especially objects used as jewelry or other consumeritems is the requirement for making the item both aesthetic andcomfortable for the user of the item. There is a need for a method ofdesigning detachable objects using magnetic force that will keep theobjects attached to the item under normal intended use while meetingaesthetics and functionality objectives.

SUMMARY

Provided is a method for designing a detachable object to an item bysetting design objectives including a magnetic holding force objectiveneeded to hold the detachable object to the item. A set of magneticpieces are selected based on the holding magnetic force objective. Anouter magnetic piece is fabricated onto the detachable object and aninner magnetic piece is fabricated and positioned within the item. Theselection of the magnetic set and/or the position of the outer and innermagnetic pieces are modified until the design objectives are met.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is an architectural diagram illustrating an exemplary embodimentwhere the holding force for detachable objects utilizes a set ofmagnets; FIG. 1B depicts a graph of magnetic flux density versusdistance from the magnet; and FIG. 1C depicts a graph of pull forceversus the distance from the magnet.

FIG. 2A depicts an architectural diagram of an exemplary embodimentwhere the inner magnetic piece of the set of magnetic pieces ispositioned within the item whereas FIG. 2B depicts an architecturaldiagram or an exemplary embodiment where inner magnetic piece ispositioned in between layers of material within the item.

FIG. 3 depicts an architectural diagram of exemplary embodimentssecuring the outer magnetic piece to the detachable object.

FIG. 4 depicts an exemplary cross sectional view of embodiments ofdetachable objects with a plurality of arrangements of the outermagnetic pieces and inner magnetic pieces.

FIG. 5 depicts an exemplar flowchart for designing and testingdetachable objects using magnetic holding force.

FIG. 6 depicts exemplary diagrams of items utilizing magnetic holdingforce for detachable objects.

DETAILED DESCRIPTION

In order to facilitate the description of the present invention, adetachable object for a shoe is utilized to illustrate an application ofthe concept.

FIG. 1A is an architectural diagram illustrating an exemplary embodimentwhere the holding force for detachable objects utilizes a set ofmagnets. The item 100 may be a shoe, handbag, purse, hat, cap, jacket,boot, suitcase, briefcase, belt, or a consumer item not sensitive tomagnets. Item 100 may also be a commercial item or industrial item notsensitive to magnets but requiring one or more detachable objects 120.The detachable object 120 comprises an ornament 104 and an outermagnetic piece 108. The ornament 104 may be jewelry or a decorativepiece. In one embodiment, the ornament 104 is made of precious metalssuch as gold, silver, platinum or the like. In another embodiment, theornament 104 utilizing one or more combination of precious metals may beadorned with diamonds and/or gemstones. The outer magnetic piece 108 iscoupled to the ornament 104 using mechanical means or by using bondingagents. Mechanical means include use of clips or applying a layer ofplating on the outer magnetic piece 108 that keeps the outer magneticpiece 108 attached to the ornament 104. Bonding agents may include metalto metal adhesives or bonding compounds. The outer magnetic piece 108may be coupled to the ornament 104 with the outer magnetic piece 108 asa base of the ornament 104 or inside a cavity (not shown) in theornament 104 such the outer magnetic piece 108 is flush to the bottomsurface of the ornament 104.

The outer magnetic piece 108 may be one or more types of magnet or oneor more pieces of permanent magnets bonded together or may be an electromagnet powered by batteries. In one embodiment, the outer magnetic piece108 may comprise magnets including rare earth, ceramic, or industrialmagnets. Rare earth magnets may include neodymium or samarium cobaltmagnets. Neodymium magnets are powerful permanent magnets and are alsoreferred to as NdFeB magnets, or NIB, because they are composed mainlyof Neodymium (Nd), Iron (Fe) and Boron (B). Neodymium magnets aretypically over ten times stronger than the strongest ceramic magnets.The material of the item 112 separates the outer magnetic piece 108 fromthe inner magnetic piece 116. The inner magnetic piece 116 may comprisemagnets including rare earth, ceramic, or industrial magnets. Similar tothe outer magnetic piece 108, the inner magnetic piece 116 may compriseone or more pieces of permanent magnets bonded together or may be anelectro magnet powered by batteries. In one embodiment, either the innermagnetic piece 116 or the outer magnetic piece may be a ferromagneticmaterial such as iron, cobalt, nickel, or various alloys including iron,cobalt, and/or nickel.

For applications that require high holding magnetic force, neodymiummagnets may be used in both the outer magnetic piece 108 and the innermagnetic piece 116. The selection of the outer magnetic piece 108 andthe inner magnetic piece 116 will be discussed below. Commerciallyavailable neodymium magnets are made from a powdered mixture that ispressed under great pressure into molds. The material is then sintered(heated under a vacuum), cooled, and then ground or sliced into thedesired shape. Coatings are then applied if required. Finally, the blankmagnets are magnetized by exposing them to a very powerful magneticfield in excess of 30,000 Oersted. Typical neodymium magnets are platedwith layers of nickel, copper, and nickel again. This triple coatingmakes neodymium magnets more durable than the more common single nickelplated magnets. Some other options for coating are zinc, tin, copper,epoxy, silver, and gold. Gold plated magnets are actually quadrupleplated with nickel, copper, nickel and a top coating of gold.

FIG. 1B depicts a graph 150 of magnetic flux density in the Y-axisversus distance from the magnet in the X-axis. Flux density is typicallymeasured in millions of Gauss Oersted (MGOe). The flux density curve 154depicts the flux density of a specific magnet as a function of distancefrom the magnet. For example, at point A in the flux density curve 154,the flux density is 1.7 MGOe for a distance of 6 millimeters from themagnet. The graph 150 of the flux density diminishes quickly as thedistance from the magnet increases. In embodiments using neodymium, thestrength of neodymium magnets is expressed in the grade, or “N rating”of the magnet, referring to the Maximum Energy Product of the materialthat the magnet is made from or the maximum strength that the neodymiumcan be magnetized to. The grade of neodymium magnets is generallymeasured in units millions of Gauss Oersted (MGOe). A magnet of gradeN42 has a Maximum Energy Product of 42 MGOe. Generally speaking, thehigher the grade, the stronger the magnet. The highest grade ofneodymium magnet currently available is N52 but magnet manufacturers arecontinuously discovering newer manufacturing techniques and processes toproduce newer and stronger magnets.

The strength of a magnet is also measured in pull force defined as theholding force of a magnet that is in contact with a flat steel plate.Pull forces are measured in pounds or kilograms. FIG. 1C depicts a graph180 of pull force in the Y-axis versus distance from the magnet in theX-axis. The pull force curve 184 depicts for a given magnet the pullforce in pounds as a function of the distance from the magnet in inches.The pull force curve 184 drops very quickly with the increase indistance. For example, point B in the pull force curve 184, the magnetis rated at 35 pounds and at point C, the magnet is rated at less than10 pounds after moving 0.05 inch from point of contact.

FIG. 2A depicts an architectural diagram of an exemplary embodimentwhere outer magnetic piece 214 of detachable object 220 comprises twomagnets and the inner magnetic piece 222 is positioned within the item200. The material 210 of the item 200 is subjected to the magnetic pullforce of the outer magnetic piece 214 and the inner magnetic piece 222.The ornament 218 includes a cavity 234 filled with the two magnets ofthe outer magnetic piece 214 where the bottom surface of outer magneticpiece 214 is flush with the upper surface of the material 210. In oneembodiment where the item is a shoe, hat, or jacket, the inner magneticpiece 222 may be wrapped in soft plastic or laminated with plastic orother material (not shown) in order to make the item more functional. Inone embodiment, the cavity 234 is disc shaped and is between 0.50 to0.75 inches in diameter and the thickness of the cavity 234 is 1/16 to1/10 of an inch, depending on the pull force needed for the outermagnetic piece 214. The outer magnetic piece 214 can be one disc magnetinstead of several stacked disc magnets. The cavity 234 can he shapedlike a disc, block, ring, arc, or half of a sphere.

As mentioned above, the outer magnetic piece 214 can be attached to theornament 218 using metal adhesives or epoxy such as J-B Weld epoxy fromJ-B Weld Company. J-B Weld epoxy uses a liquid steel/epoxy resin and ahardener. The mixture comprising the epoxy and the hardener sets in 4 to6 hours and cures fully in 15 to 24 hours. In one embodiment, the cavity234 is cleaned with a solvent such as acetone, ethyl acetate, or thelike and left to dry. The side of the outer magnetic piece 214 to beattached to the ornament 218 in the cavity 234 is lightly sanded tocreate a better bonding texture. The epoxy resin is then mixed with thehardener, creating a chemical reaction that turns the mixture into ahard compound after a curing process. This compound is placed inside therecessed cavity 234 of the ornament 218 and the outer magnetic piece 214is placed inside the cavity 234. The compound covers the lower side andthe surrounding edges of the outer magnetic piece 214 for a better hold.Once cured, the bottom area of the outer magnetic piece 214 andproximate area of the ornament 218 are lightly sanded to create a smoothand even surface and appropriate color paint is applied to cover thecolor of the compound. Other metal adhesives and hardening materials maybe used. If the ornament 218 is made of gold, silver, platinum, oralloys, then an appropriate metal paint is used to make ornament 218 andthe outer magnetic piece 214 blend in color and texture.

FIG. 2B depicts an architectural diagram of an exemplary embodimentwhere inner magnetic piece 222 is positioned in between layers 226 and230 of material 210 within the item 250. For example, in the case wherethe ornament 218 is jewelry and the item 250 is a shoe, the innermagnetic piece 222 is inserted between two materials 226 and 230 of theshoe 250. In another example where the item 250 is a briefcase, theinner magnetic piece 222 is inserted between two materials 226 and 230of the briefcase.

FIG. 3 depicts an architectural diagram of an exemplary embodiment wherethe outer magnetic piece 308 is secured to the detachable object 304. Asmentioned above, the outer magnetic piece 308 can be attached to thedetachable object 304 using a disc magnet with or without using a cavityas in 3A or by using a block magnet with or without using a cavity as in3B or by using a ring magnet with or without using a cavity as in 3C orusing a strip magnet with or without using a cavity as in 3D or by usinga wire magnets with or without using a cavity as in 3E. To oneknowledgeable in the art, other variations of the shape and method ofattachment of the outer magnetic piece to the ornament exist that arewithin the scope and concepts of the invention.

FIG. 4 depicts an exemplary cross sectional view 400 of the embodimentsof detachable objects with a plurality of arrangements of outer magneticpieces and inner magnetic pieces. In 4A, the detachable object 414comprising the ornament 404 and the outer magnetic piece 406 utilizes asingle block magnet attached to the ornament 404 where the innermagnetic piece 410 comprises three magnets enclosed in container 412 andplaced against the material 408 of item 414. In one example, the item400 may be a briefcase or luggage piece where the inner magnetic piece410 comprises three magnets inside an container 412, attached to theinside of the briefcase or luggage piece. In 4B, arc magnets are used.These are special magnets where the magnetic blanks are radiallymagnetized. The outer magnetic piece 426 is attached to the ornament 424where the arc angle follows the outer curvature of the material 428 ofthe item 420. Similarly, the inner magnetic piece 430 can be an arcmagnet where the arc angle follows the inner curvature of the material428 of the item 420. In 4C, the outer magnetic piece 466 comprises threemagnets attached to the ornament 464 to form the detachable object 474.The inner magnetic piece 470 comprises a magnetic sheet or flexiblemagnetic slab positioned against the material 468 of the item 460. Aninner magnetic piece 470 in the form of a magnetic sheet or flexiblemagnetic strip provides flexibility in positioning the detachable object474 anywhere in the area covered by the inner magnetic piece 470. To oneknowledgeable in the art, other variations of the configuration andnumber and shape of the outer and inner magnetic pieces exist that arewithin the scope and concepts of the invention.

FIG. 5 depicts an exemplary flowchart for designing and testingdetachable objects using magnetic holding force. In step 500, designobjectives for a detachable object are set. The design objectives caninclude a holding force that keeps the detachable object attached to theitem. The holding force may be based on empirical data correlating theweight and size of the detachable object and distance of the outermagnetic piece to the inner magnetic piece to the effective holdingforce of the magnetic set. Magnetic holding force may be expressed aseffective pull force or magnetic flux density and the distance to themagnet as depicted in the graphs in FIGS. 1B and 1C. Other designobjectives for the detachable object may include aesthetic appealespecially for jewelry, and decorative items. Another design objectivemay be functionality, defined as the ability of the item in the presenceof the detachable object(s) allowing unimpeded use of the item for itsnormal intended purpose. For example, if the detachable object isjewelry or decorative article for a shoe, the detachable jewelry ordecorative article and the attachment technique should allow for regularnormal use of the shoe. In step 504, a magnetic set is selected based onthe initial holding force objective. The magnetic set comprises theouter and inner magnetic pieces. As mentioned above, the outer or theinner magnetic piece may include one or more magnets. Furthermore, theouter magnetic piece may be a ferrite material, i.e., attracted tomagnets such as iron, copper, nickel, or alloys including at least oneof iron, copper, or nickel. Similarly, the inner magnetic piece may be amagnet or a ferrite material. The shape and dimensions of the outer andinner magnetic pieces are determined based on the type and number ofdetachable objects designed for the item. In one embodiment, the item isa shoe and the detachable object is jewelry. The jewelry may use gold,silver, platinum, or the like and may be adorned with diamonds and/orprecious stones. The outer magnetic piece can include a neodymium blockor disc magnet or an electromagnet and the inner magnetic piece may be adisc neodymium magnet or a ferrite material. In another embodiment, theitem is a bag or purse and the detachable object is a set of decorativejewelry. The outer magnetic piece can be a set of magnets, one for eachpiece of decorative jewelry and the inner magnetic piece can be aflexible sheet of rare earth magnet such as neodymium or samarium cobaltmagnets or a flexible sheet of ferrite material placed in between layersof the material of the bag or purse.

In step 508, the process of attaching the outer magnetic piece isdetermined. As mentioned above, the outer magnetic piece may be attachedto the ornament using the appropriate adhesive. In one embodiment, acavity is used for attaching the outer magnetic piece to the ornament.If the detachable object is jewelry or decorative article, a cavity maybe utilized to conceal or minimize the profile of the outer magneticpiece, thus enhancing the aesthetic appeal of the detachable object. Theouter magnetic piece may be placed in a cavity slightly larger than theouter magnetic piece, attached to the ornament with metal adhesive,where the exposed side of the outer magnetic piece is lightly sanded andpainted with appropriate paint to match or complement the color of theornament. In another embodiment, instead of painting, the exposed sideof the outer magnetic piece is covered with plating material such asgold, silver, or platinum and the like. In step 512, the design andpositioning of the inner magnetic piece is determined. The design andpositioning of the inner magnetic piece is based on the intended normaluse of the item. For example, if the item is a shoe, the inner magneticpiece needs to be easy to position and must not impede in the use of theshoe. In one embodiment where the item is a shoe, the inner magneticpiece is a neodymium disc magnet with a diameter of ½ to ¼ inch andthickness of 1/32 to 1/16 of an inch and the magnet is placed inside theshoe on top of the foot. Alternatively, the magnet may be taped insidethe shoe proximate to the position of the detachable object.

In step 516, the outer magnetic piece is fabricated onto the detachableobject using the design determined in step 508. In step 520, the innermagnetic piece is fabricated onto the item or positioned on the item. Ifthe inner magnetic piece is a sheet of ferrite material or a magneticsheet, the inner magnetic piece can be attached to the item orfabricated in between layers of material of the item. If the innermagnetic piece was designed to be placed on or taken off, then the innermagnetic piece is positioned as designed in step 512. For example, itthe item is a shoe and the detachable object is jewelry or decorativearticle, this step can be positioning the inner magnetic piece insidethe shoe on top of the foot. In step 524, the performance of thedetachable object is compared to the design objectives. For example, ifthe design objectives of a detachable object include a holding force of50 pounds for the detachable object such as shoe jewelry andfunctionality as a shoe, these objectives are compared with the actualperformance of the shoe jewelry. If the objectives are not met, thedesign of the magnetic set, i.e., the outer and inner magnetic piecesare modified and processes in steps 508, 512, 516, 520, and 524 areiterated until the design objectives are met.

FIG. 6 depicts exemplary diagrams of sample items 600 utilizing magneticholding force for detachable objects. Several items are depicted thatmay use one or more detachable objects. One item 610 is a shoe 614 shownwith one detachable object 618 where the inner magnetic piece (notshown) would be placed by wearer on top of the foot proximate todetachable object 618. Other items depicted, 630, 650, and 670,illustrate a handbag 634, a briefcase 654, and a hat 674 and a pluralityof detachable objects, 638, 658, and 678 respectively. Many others suchas caps, jackets, boots, belts, and other consumer items may beaccentuated with detachable objects using the principles and concepts ofthe present invention. Other applications including commercial and/orindustrial items such as appliances and furniture can also be adornedwith detachable objects.

Although exemplary embodiments have been described, variousmodifications can be made without departing from the spirit and/or scopeof the present invention. For example, mobile and regular phones mayutilize detachable objects. Interiors and exteriors of cars andrecreational items such as motorcycles, and boats may use the conceptsand principles described with the present invention. Therefore, thepresent invention should not be construed as being limited to thespecific forms shown in the drawings and described above.

1. A method of designing a detachable object for an item, the methodcomprising: setting one or more design objectives for designing adetachable object for an item using magnetic force wherein one objectiveis a holding magnetic force objective; selecting a magnetic set based onthe determined holding magnetic force, the magnetic set including anouter magnetic piece and an inner magnetic piece; determining a processof attaching the outer magnetic piece to the detachable object;determining a design and position of the inner magnetic piece in theitem; fabricating the outer magnetic piece onto the detachable objectand positioning the inner magnetic piece in the item; if the one or moredesign objectives are not met, modifying the selection of the magneticset and/or position of the inner magnetic piece and iteratingdetermining the process of attaching the outer magnetic piece onto thedetachable object, determining the design and position of the innermagnetic piece in the item, fabricating the outer magnetic piece ontothe item and positioning the inner magnetic piece until the one or moredesign objectives are met.
 2. The method of claim 1 wherein the holdingmagnetic force is provided by neodymium magnets, samarium cobaltmagnets, or electro magnets.
 3. The method of claim 2 wherein theneodymium magnets have a rating of N42, N50, or higher.
 4. The method ofclaim 1 wherein the item is a shoe and the detachable object is shoejewelry.
 5. The method of claim 4 wherein the outer magnetic piece is adisk neodymium magnet.
 6. The method of claim 4 wherein the outermagnetic piece is a square, ring, strip, rectangular, or cylindricalneodymium magnet.
 7. The method of claim 1 wherein the inner magneticpiece is a disc or block neodymium magnet securely positioned betweentwo layers of materials of the shoe.
 7. The method of claim 1 whereinthe inner magnetic piece is disc or plate neodymium magnet varying inthickness from 1/16 inch thickness to 1/32 inch thickness or less. 8.The method of claim 1 wherein the inner magnetic piece is a flexiblesheet of neodymium magnet.
 9. The method of claim 1 wherein the innermagnetic piece is ferrite magnet or a flexible sheet of ferritematerial.
 10. The method of claim 1 wherein the fabricating the outermagnetic piece onto the detachable object comprises: creating a cavityin the detachable object wherein the cavity is slightly larger than theouter magnetic piece; and attaching the outer magnetic piece to thedetachable object using the cavity.
 11. The method of claim 10 whereinthe outer magnetic piece is attached to the detachable object usingmetal adhesive.
 12. The method of claim 1 wherein the outer magneticpiece comprises two or more neodymium magnets attached to the detachableobject.
 13. The method of claim 1 wherein the detachable object isjewelry made of gold, silver, platinum, or any combination of theforegoing.
 14. The method of claim 1 wherein the detachable object isjewelry made of precious metals or jewelry made of precious metalsdecorated with diamond and/or gemstones.
 15. The method of claim 1wherein the item is a shoe, handbag, purse, hat, cap, jacket, boot,suitcase, briefcase, or belt.
 18. The method of claim 1 wherein theouter magnetic piece is painted with a color substantially close to thecolor of the surrounding portions of the detachable object.
 17. Themethod of claim 1 wherein modifying the selection of the magnetic setand/or position of the inner magnetic piece includes changing thethickness of the inner magnetic piece or changing the inner magneticpiece to a sheet magnet or flexible magnet.
 18. An apparatus fabricatedto keep a detachable object attached to an item under normal intendeduse, the system comprising: an item having a normal intended use; adetachable object configured to be attached to the item using a set ofmagnetic pieces, the set of magnetic pieces comprising: an outermagnetic piece coupled to the detachable object; and an inner magneticpiece positioned within the item; wherein the outer magnetic piece andthe inner magnetic piece are configured to generate a holding magneticforce sufficient to keep the detachable object attached to the itemunder normal intended use.
 19. The apparatus of claim 18 wherein theholding magnetic force is provided by neodymium magnets, samarium cobaltmagnets, or electro magnets.
 20. The apparatus of claim 18 wherein theneodymium magnets have a rating of N42, N50, or higher.
 21. Theapparatus of claim 18 wherein the item is a shoe and the detachableobject is shoe jewelry.
 22. The apparatus of claim 18 wherein the outermagnetic piece is a disk neodymium magnet or block neodymium magnet. 23.The apparatus of claim 18 wherein the outer magnetic piece is a square,ring, strip, rectangular, or cylindrical neodymium magnet.
 24. Theapparatus of claim 18 wherein the inner magnetic piece is a discneodymium magnet securely positioned between two layers of materials ofthe item.
 25. The apparatus of claim 18 wherein the inner magnetic pieceis flexible sheet neodymium magnet or wherein the inner magnetic pieceis a ferrite magnet or a flexible sheet of ferrite material.
 26. Theapparatus of claim 18 wherein outer magnetic piece is coupled to thedetachable object by creating a cavity in the detachable object whereinthe cavity is slightly larger than the outer magnetic piece.
 27. Theapparatus of claim 18 wherein the outer magnetic piece is attached tothe detachable object using epoxy resin and a hardener.